In the manufacture of metal cans, such as out of aluminum or steel sheets, it is common to coat one surface of the sheet before cutting and processing into can sizes and shapes. Typically, such coating is performed by the use of a coating roller which is a relatively large size cylinder, as for example a twelve to fifteen inch diameter and a two to four foot length cylinder, whose outer surface is covered with a resilient elastomer layer that functions as the coating applying surface.
Conventionally, coating rollers of the above described type, are made by first, forming the metal drum and second, casting or molding upon the peripheral surface of the drum the elastomer layer. In order to assure uniformity of coating application, the layer itself must be of an accurate thickness, both longitudinally and concentrically relative to the drum axis. Thus, usually after the layer is applied upon the drum surface, the composite roller-layer cover must be ground or otherwise machined to provide the accurate outer surface.
In use of such rollers, when the elastomer layer wears so as to be out of tolerance or when a roller is changed for another to accomodate to a different kind of coating to be applied to the sheet metal, it is typical to remove the entire roller and replace it with a fresh roller. The used roller is then typically stripped of its plastic and resurfaced.
Thus, in the lines which utilize coating rollers, it is ordinarily necessary to keep a supply of spare rollers available to interchange with worn surface rollers or rollers used for a different coating than needed at the moment.
Such rollers are relatively expensive and in addition, a considerable amount of down time is involved in changing one roller for another. For example, in a typical operation for coating sheet steel or sheet aluminum in a can making process, it could take somewhere between an hour and a quarter to an hour and a half to remove and replace a roller, during which time the line is shut down. In addition, the expense of maintaining spare rollers, and then shipping a used roller to a roller processor and then resurfacing and returning the roller, is relatively expensive.
Hence, the invention herein relates to an improved coating roller which utilizes a removable outer layer or blanket which can be rapidly changed with a fresh cover without the necessity of pulling the roller itself out of the operating position in a manufacturing line, to thereby eliminate the expense and time loss in replacing rollers and in resurfacing rollers.